As the destruction of the environment and the depletion of resources are becoming severe, interest in a system capable of storing energy and effectively utilizing the stored energy is increasing. There has also been an interest in new renewable energy, which does not cause pollution or minimizes pollution during a power generation process. An energy storage system has recently undergone research in accordance with these environmental considerations and environmental changes. The energy system may be a system for connecting new renewable energy and a battery system for storing power.